Synthesis of an Ultra-Bright Rotaxane with Threaded BODIPY Stoppers

Area of Science:

• Supramolecular Chemistry
• Organic Chemistry
• Materials Science

Background:

• Boron-containing rotaxanes are of interest for their unique properties.
• Developing novel fluorescent molecular architectures is a key research area.

Purpose of the Study:

• To synthesize a novel boron-assembled rotaxane with BODIPY stoppers.
• To investigate the fluorescence properties of the rotaxane and its precursor.
• To explore the effect of selective deborylation on fluorescence.

Main Methods:

• Synthesis of a boron-assembled rotaxane precursor with three boron atoms.
• Selective removal of one boron atom using potassium hydroxide.
• Characterization of fluorescence properties, including quantum yield and brightness.

Main Results:

• The nonfluorescent precursor transformed into a highly fluorescent rotaxane upon selective deborylation.
• The resulting rotaxane exhibited a fluorescence quantum yield of 64%.
• The rotaxane demonstrated high brightness (1.24 × 10^5 mol^-1·L·cm^-1) due to its high absorption coefficient.

Conclusions:

• Selective deborylation is an effective strategy to activate fluorescence in boron-assembled rotaxanes.
• The synthesized BODIPY-stoppered rotaxane is a promising candidate for applications requiring bright fluorescence.